OMI-DB Statistics

The OPTIMAM1 project was initiated in 2008, aiming to optimise the adoption of new X-ray technology for detecting breast cancers and thereby to improve the early detection of breast cancers in the NHS Screening Programme. OPTIMAM1 was followed by OPTIMAM2 (2013). The Scientific Computing team, at the Royal Surrey NHS Foundation Trust is responsible for the maintenance of the OPTIMAM Database (OMI-DB), which contains over 8,000,000 processed and unprocessed FFDM, Tomosynthesis and MR images. Screening information is collected from National Breast Screening System (NBSS). Sets of normal, benign and malignant images are selectively collected from multiple NHS sites.

OMI-DB comprises multiple screening datasets (episodes) from multiple clients (cases) who may or may not have been identified with a benign/malignant lesion. Each client's screening dataset contains two views of each breast (medio-lateral oblique and cranio-caudal). Associated tools have been developed to:

• identify patient cases of interest from the National Breast Screening System (NBSS)
• automatically retrieve corresponding images from the site’s PACS together with any associated radiological, clinical and pathological data from local databases that may be of interest
• de-identify collected images
• allow remote expert radiologists to annotate the images with interesting clinical features and provide descriptors of these features.

All collected cases retrieved from the database are classified as Normal, Benign, Malignant, or Interval Cancers. The Malignant cases are sub-classified into Malignant-Marked and Malignant-Unmarked, depending on if they have been annotated by an OPTIMAM expert image reader or not. The definitions are:

• Interval Cancer: symptomatic cases in the current year which are classified as malignant after a previous screening appointment at which a client received a normal result and before their next scheduled screening appointment, or previously classified as interval cancer
• Malignant: cases that are classified as malignant by either surgery, or biopsy, or previously classified as malignant
• Benign: cases that are classified as benign by either surgery, or biopsy, or previously classified as benign
• Normal: cases not classified as malignant or benign, or interval cancer

It should be noted that some clients have multiple events in different years.

A high level summary of all data in OMI-DB is given in the table below.

Aggregate statistics describing the portion of OMI-DB available for sharing are given in the tables below. These statistics describe the number of clients or episodes for various characteristics of the data.